This invention relates in general to sputter ion pumps and is particularly directed to a new and improved sputter ion pump for particle beam optical instrumentation. Sputter ion pumps are old and well known as typically shown and their operation explained, for example, in the U.S. Patent to Jepsen, No. 3,094,639, the U.S. Patent to Lloyd, et al., No. 3,042,824, or as described in an earlier U.S. Patent to Hall, et al., No. 2,993,638.
The pump cells (anode and cathode) of these sputter ion pumps are the building blocks of an ion pump and are usually placed in a vacuum chamber and packaged in self-contained units with flanges. The units are then typically connected, as an appendage, to a chamber, pipe, or optical column. As an appendage, however, the ion pump, being magnetic, tended to distort the operation of the particle beam in the optical column and also required the optical column and thus the beam path to be longer than desired. Thus, in the particle beam application, if the magnetic circuit and pumping cell distribution are suitably arranged, other instrumentation, such as valves, apertures, etc., could be used without additional bore length. This would result in a compact highly integrated structure. Also, if appropriately arranged, not only can the residual magnetic fields be minimized and a compact structure attained, but according to the teachings of this invention the magnetic field of the ion pump can be utilized for particle beam focusing.